Approximately 80% of cases of urinary incontinence are cause by a condition known as urinary sphincter mechanism incompetence (USMI). This can be a congenital or acquired condition and can affect both sexes, although is probably more recognised in bitches. There are several factors that contribute to USMI including both structural or functional abnormalities. These consist of reduced urethra tone, a shorter urethral length, abnormal bladder position (those located within the pelvis), larger dog breeds, spaying (surgical removal or the reproductive tract), hormones and obesity.
The association between spaying and urinary incontinence has been widely investigated. It is speculated to be caused by reduced circulating oestrogens thus the hormonal influences are suspected to be a factor. There is currently a lack of conclusive evidence as to whether spaying before their first season increases risk of incontinence later in life (>10 years) and remains a debate in the veterinary profession. Obesity, albeit not a direct cause, can also worsen the degree of incontinence most likely due to increased abdominal pressure on the bladder.
Medical treatment consists of firstly ruling out a urinary tract infection if present. Your vet can determine this from a urine sample which is often sent off for culture and sensitivity testing at an external laboratory to confirm eradication. Further investigations can confirm whether there is a systemic condition such as diabetes or Cushing disease present which may exacerbate or precipitate incontinence, particularly if your pet is drinking and urinating more than usual.
On veterinary recommendation its might be suggested to put your pet on a weight loss diet if they are obese to help reduce urine leakage. If above issues are addressed then your veterinarian may prescribe medication to increase urethral tone.
Short acting oestrogen licensed to treat urinary incontinence in bitches. Often used first line as relatively inexpensive and infrequently administered. Lower risk of adverse side effects though can cause bone marrow suppression in some cases which requires ongoing monitoring and potentially blood tests. Comes in tablet formulation.
If your dog has a structural abnormality present such as ectopic ureters surgical correction is most commonly indicated to correct the position to avoid urine leakage by allow urine to drain into the bladder rather than at the entrance to the bladder (bladder neck) and urethra. If your dog is affected by bladder stones then further imaging may be indicated, most commonly x-rays or contrast radiographs to outline radiolucent stones in the urinary tract.
Once confirmed surgical intervention may be required to remove the stones or alternatively a dissolution diet may be indicated to dissolve the stones depending on the type present. Alternatively if radiographs confirm that the bladder neck is located within the pelvis (termed intrapelvic bladder neck) then this may need to be relocated surgically to anchor it in the normal abdominal position.
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